how to check if a string is an integer javascript

var myString     =  "abc123";
var otherString  =  "123";
/* isInterger() checks if an value repersents an int  */

isInteger(myString);    //returns false
isInteger(otherString); //returns true

if (typeof myVar === 'string'){
    //I am indeed a string
}

// native returns true if the variable does NOT contain a valid number
isNaN(num)

// can be wrapped for making simple and readable
function isNumeric(num){
  return !isNaN(num)
}

isNumeric(123)         // true
isNumeric('123')       // true
isNumeric('1e10000')   // true (This translates to Infinity, which is a number)
isNumeric('foo')       // false
isNumeric('10px')      // false

function isInt(str) {
  return !isNaN(str) && Number.isInteger(parseFloat(str));
}

var myString     =  "abc123";
var otherString  =  "123";
/* isInterger() checks if an value repersents an int  */

Number.isInteger(myString);    //returns false
Number.isInteger(otherString); //returns true

isNaN(num)         // returns true if the variable does NOT contain a valid number